Acid Monoesters Research Articles

The Effect of Diesters and Lauric Acid on Rheological Properties of Air/Water Interfaces Stabilized by Oligofructose Lauric Acid Monoesters

In this study, the rheological properties of interfaces stabilized by oligofructose fatty acid esters were elucidated. First, the properties of interfaces stabilized by monoesters (ME), diesters (DE), lauric acid (LA), oligofructose (OF), and mixtures of ME with DE, LA, or OF were studied. Second, the properties of interfaces stabilized by the crude product (CP) containing ME, DE, LA, and OF were studied. The dependency of the dilatational modulus on frequency and deformation amplitude indicated the possible formation of a soft glass phase for ME, and a viscous interface for DE. When ME and DE were mixed at a ratio of 0.8/0.2, the experimental results suggest that the interfacial structure consists of islands of a glass phase formed by ME, dispersed in a 2D viscous phase of DE. CP stabilized interfaces, where the ratio ME/DE was higher, lead to a different rheological response. The ratio ME/DE plays an important role in the surface properties of the CP. This may have significant consequences for applications in macroscopic systems such as foams.

Asymmetric phthalates—A special case for risk assessment

Phthalic acid diesters are ubiquitously present in the environment due to their intensive use as plasticizers. Human exposure to these contaminants has been proved by determining phthalates and their metabolites in human urine and blood. Particular phthalates with ester chain lengths of C4-C6 possess reprotoxic properties [T. Lovekamp-Swan & B. J. Davis, Environmental Health Perspectives 111 (2003) 139–145]. Asymmetric phthalic acid diesters with “critical” C4–C6 chain lengths have been pre-registered in REACH but information on their human metabolism is scarce. Theoretically, two different monoesters with either “critical” or “uncritical” ester moieties may be formed. Thus, for an adequate assessment of possible health risks of asymmetric phthalic acid esters it is essential to know, which of the monoesters are preferably formed by human metabolism. In order to gain insight into the metabolism of asymmetric phthalates, conversion of 11 asymmetric phthalic acid diesters was investigated by in vitro hydrolysis experiments using rat and human liver S9 homogenates. All asymmetric phthalates were fast hydrolysed into mixtures of both possible monoesters and as consequence; organisms are exposed to mixtures of phthalic acid monoesters. Based on these results, the risk assessment of asymmetric phthalic acid diesters seems to be more complex than that of symmetric phthalates because two different monoesters can be formed. This has implications for the risk assessment and the exposure assessment, as in case of asymmetric phthalic acid diesters with a critical chain length, the same metabolites can be formed which are responsible for the reprotoxic effects of already classified reprotoxic phthalates

Synthesis of Phosphaisocoumarins through Rhodium-Catalyzed Cyclization Using Alkynes and Arylphosphonic Acid Monoesters

A rhodium-catalyzed cyclization using alkynes and arylphosphonic acid monoesters for the synthesis of phosphaisocoumarins is reported. A number of arylphosphonic acid monoesters were selectively cyclized in high yields with functional group tolerance. In addition, unsymmetrical alkynes are applied in high regioselectivity.

Synthesis and in vitro antitumor activities of lupeol dicarboxylic acid monoester derivatives

Ten lupeol dicarboxylic acid monoester derivatives as new potent antitumor agents were synthesized and evaluated for in vitro antitumor activities against A549, LAC, HepG2 and HeLa cell lines. Among them, compounds 1-5 showed excellent antitumor activities against all tested tumor cell lines and compounds 6-10 exhibited high activities against A549, HepG2 and HeLa cells, exceeded lupeol, lupanol and doxorubicin. Compound 2 displayed the highest potent antitumor activities with IC50 values of 5.78μM against A549 cell, 2.38μM against LAC cell, 6.14μM against HepG2 cell and 0.00842μM against HeLa cell.

Synthesis and characterization of raffinose fatty acid monoesters under ultrasonic irradiation

Raffinose long-chain fatty acid monoesters, which were acylated at the 1 and 6 positions, were synthesized by the acylation of raffinose with aliphatic methyl esters under reduced pressure and ultrasound irradiation. Synthesis yields ranged from 15 to 44 %. The optimum reaction conditions for the acylation reaction include a molar ratio of raffinose to fatty acid methyl ester of 2:1, quantity of anhydrous K2CO3 accounted for raffinose of 12 % mol, ultrasonic temperature of 65 °C, ultrasonic time of 2 h, and reaction pressure of 10 kPa. The acylation had good monoester selectivity and the raffinose monoesters structural confirmation was obtained by infrared spectroscopy, electrospray ionization mass spectrometry, and nuclear magnetic resonance. These surfactants had a higher percentage of monoesters and the ratio of 1-O-monoester/6-O-monoester is 2.2–2.6. They all had ideal hydrophile–lipophile balance value with similar melting properties. .

Exposure to phthalic acid, phthalate diesters and phthalate monoesters from foodstuffs: UK total diet study results

Phthalates are ubiquitous in the environment and thus exposure to these compounds can occur in various forms. Foods are one source of such exposure. There are only a limited number of studies that describe the levels of phthalates (diesters, monoesters and phthalic acid) in foods and assess the exposure from this source. In this study the levels of selected phthalate diesters, phthalate monoesters and phthalic acid in total diet study (TDS) samples are determined and the resulting exposure estimated. The methodology for the determination of phthalic acid and nine phthalate monoesters (mono-isopropyl phthalate, mono-n-butyl phthalate, mono-isobutyl phthalate, mono-benzyl phthalate, mono-cyclohexyl phthalate, mono-n-pentyl phthalate, mono-(2-ethylhexyl) phthalate, mono-n-octyl phthalate and mono-isononyl phthalate) in foods is described. In this method phthalate monoesters and phthalic acid are extracted from the foodstuffs with a mixture of acidified acetonitrile and dichloromethane. The method uses isotope-labelled phthalic acid and phthalate monoester internal standards and is appropriate for quantitative determination in the concentration range of 5–100 µg kg–1. The method was validated in-house and its broad applicability demonstrated by the analysis of high-fat, high-carbohydrate and high-protein foodstuffs as well as combinations of all three major food constituents. The methodology used for 15 major phthalate diesters has been reported elsewhere. Phthalic acid was the most prevalent phthalate, being detected in 17 food groups. The highest concentration measured was di-(2-ethylhexyl) phthalate in fish (789 µg kg–1). Low levels of mono-n-butyl phthalate and mono-(2-ethylhexyl) phthalate were detected in several of the TDS animal-based food groups and the highest concentrations measured corresponded with the most abundant diesters (di-n-butyl phthalate and di-(2-ethylhexyl) phthalate). The UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) considered the levels found and concluded that they did not indicate a risk to human health from dietary exposure alone.

An Efficient Large-Scale Synthesis of a Naphthylacetic Acid CRTH2 Receptor Antagonist

An efficient and practical synthesis of a naphthylacetic acid CRTH2 receptor antagonist is reported. Michael addition of ethyl t-butyl malonate to an allenoate afforded a triester, which was selectively hydrolyzed and decarboxylated to give a benzylidenepentanedioic acid monoester. Treatment of this compound with potassium acetate and acetic anhydride produced the naphthylacetate core. The triflate of the key building block was coupled with a zinc reagent of the side chain under improved Negishi coupling conditions to afford the target product. The process was successfully scaled up to produce over 2 kg of the API.

ChemInform Abstract: Enzyme‐Mediated Enantioselective Hydrolysis of Dicarboxylic Acid Monoesters.

AbstractThe separation of the reaction products is accomplished by a simple extraction procedure.

CAL-B catalyzed desymmetrization of 3-alkylglutarate: “olefin effect” and asymmetric synthesis of pregabalin

CAL-B catalyzed desymmetrization of prochiral 3-alkylglutaric acid diesters was performed to prepare optically active 3-alkylglutaric acid monoesters bearing various alkyl substituents, including methyl, ethyl, propyl and allyl groups. Allyl esters showed far better stereoselectivity among the alkyl esters, suggesting possible π-π interactions between the olefin of the substrate and the Trp104 or His224 side chains at the enzyme active site. Based on this reaction, the synthesis of (S)-(+)-3-aminomethyl-5-methylhexanoic acid (pregabalin) was achieved with a 70% overall yield.

Novel surface-active oligofructose fatty acid mono-esters by enzymatic esterification

This article describes the synthesis of a series of oligofructose monoesters with fatty acids of different chain length (C8, C12, C16 and C18) to obtain food-grade surfactants with a range of amphiphilicity. Reactions were performed in a mixture of DMSO/ButOH (10/90 v/v) at 60°C and catalysed by immobilised Candida antarctica lipase B. MALDI-TOF-MS analysis showed that the crude reaction products were mixtures of unmodified oligofructose and mostly mono-esters. The conversion into mono-esters increased with the length of the fatty acid chain, reflecting the specificity of the lipase towards more lipophilic substrates. Reverse phase solid phase extraction was used to fractionate the products, which lead to sufficient purity (>93%) of the fatty acid esters for functionality testing. It was shown that derivatives of longer (C16 and C18) fatty acids were more efficient in lowering surface tension and gave a much higher dilatational modulus than derivatives of the shorter (C8 and C12) fatty acids.

Metabolomics Identifies an Inflammatory Cascade Involved in Dioxin- and Diet-Induced Steatohepatitis

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is among the most potent environmentally toxic compounds. Serum metabolomics identified azelaic acid monoesters as significantly increased metabolites after TCDD treatment, due to downregulation of hepatic carboxylesterase 3 (CES3, also known as triglyceride hydrolase) expression in an arylhydrocarbon receptor (AhR)-dependent manner in mice. The decreased CES3 expression was accomplished by TCDD-stimulated TGFβ-SMAD3 and IL6-STAT3 signaling, but not by direct AhR signaling. Methionine- and choline-deficient (MCD) diet-treated mice also showed enhanced serum azelaic acid monoester levels after attenuation of hepatic CES3 expression, while db/db mice did not, thus suggesting an association with steatohepatitis. Forced expression of CES3 reversed serum azelaic acid monoester/azelaic acid ratios and hepatic TGFβ mRNA levels in TCDD- and MCD diet-treated mice and ameliorated steatohepatitis induced by MCD diet. These results support the view that azelaic acid monoestersare possible indicators of TCDD exposure and steatohepatitis and suggest a link between CES3, TGFβ, and steatohepatitis.

Enzyme-Mediated Enantioselective Hydrolysis of Dicarboxylic Acid Monoesters

Enzyme-Mediated Enantioselective Hydrolysis of Dicarboxylic Acid Monoesters

Two-Fold Modification of the Phenyl Substituent in Phenylphosphonic Acid Monoester Monoamides

Phenylphosphonic acid ethyl ester N,N-diethylamide was subjected to a double modification of its phenyl substituent through directed ortho-metalation followed by dearomatization of the aryl substituent under Birch reduction conditions. Application of the same methodology to a diastereomerically pure phenylphosphonic acid monoester monoamide led to the formation of P-stereogenic cyclohexadienyl-phosphonic acid derivatives. The method offers a simple and efficient modification of phenyl substituent in organophosphorus compounds.

Synthesis and Emulsification Properties of Organosilicone Modified Sodium Sulfonate of Alkanolamide Succinic Acid Monoester with Palm Oil

Abstract Surfactants are widely used in the leather-making processes. The structure and property of surfactant obviously affect the quality and performance of leather. In this paper, a novel anionic surfactant, organosilicone modified sodium sulfonate of alkanolamide succinic acid monoester with palm oil was synthesized. Firstly palm oil was amidated with diethanolamine, then grafted with hydroxy-terminated silicone oil, esterified with maleic anhydride and sulphited with sodium bisulfite in sequence. The emulsification properties and fatliquoring performance of the prepared surfactant were tested. The influence of the mass percentage of reactants, the reaction temperature and time on the surface tension, the emulsifying activity and stability of the prepared surfactant were investigated. The FT-IR spectra analysis showed that under optimised conditions the novel surfactant was obtained. The fatliquoring application experiments showed that the novel surfactant is an excellent leather fatliquor.

Alkaline Phosphatase-Responsive Anodic Electrochemiluminescence of CdSe Nanoparticles

Alkaline phosphatase (ALP) catalyzes the hydrolysis and transphosphorylation of a wide variety of phosphoric acid monoesters and plays an important role in clinical diagnosis. In this work, an ALP-responsive anodic electrochemiluminescence (ECL) system based on coreaction of CdSe nanoparticles (NPs) and triethylamine has been designed for facile detection of ALP. The substrate of ALP, i.e., phenyl phosphate salt, shows no effect on the ECL emission whereas its catalytic product of phenol may induce ECL inhibition. For the buffer containing phenyl phosphate, the ECL emission is found to decline in the presence of ALP with different incubation time. The mechanism investigations indicate that the deposition of the electropolymerized phenol products may compete with the electrophoretic-driven adsorption of CdSe NPs on glassy carbon electrode and induce the ECL inhibition, which can be demonstrated by scanning electron microscopy, energy dispersive spectrometry, and anodic stripping voltammetry. Therefore, an inhibition type strategy has been developed to sensitively detect ALP ranging from 0.5 to 6.4 nM (activity ca. 2-25 U/L), with a detection limit of 0.5 nM. The potential interference from the common proteins is negligible. The recovery of ALP in diluted serum samples ranges from 91 to 114%, implicating its potential applications in the complex biological matrixes.

Determination of Trace Phthalic Acid Monoesters in Sediments and Soils by GC-MS

A simple procedure for determining trace phthalic acid monoesters (PAMs) in sediments/soils was developed. The method used ultrasonic extraction, silylation derivatization, and GC-MS. After ultrasonic extraction, the supernatants were reextracted with dichloromethane, silylated, and did not require further clean-up before GC-MS analysis. Effects of parameters, such as extraction solvents, pH of water as extraction solvent and sediment/soil properties, on the recovery of PAMs were studied. Five sediments from Tianjin city and one red soil from Jiangxi province were used. The results showed that organic carbon (OC) content played an important role in the recovery of PAMs. The optimal extraction solvent for sediments/soils with >1% of OC content and high CEC was 0.01 M HCl aqueous solution and pure water was better for sediments/soils with <1% of OC content. In 5 g sediment/soil sample (dry weight), the method detection limit (MDL) was below 0.04 ng/g for mono-n-butyl phthalate (MBP) and 0.02 ng/g for mono-(2-ethylhexyl)-phthalate (MEHP). Average recoveries of MBP and MEHP were 81.6%−105.2% and 76.0%−95.6%, respectively, with relative standard deviations ≤ 6.6%. MBP and MEHP in the sediment and soil samples studied were detected at levels of 9.2–57.1 and 13.0–166.7 ng/g, respectively.

β,γ-CHF- and β,γ-CHCl-dGTP Diastereomers: Synthesis, Discrete 31P NMR Signatures, and Absolute Configurations of New Stereochemical Probes for DNA Polymerases

Deoxynucleoside 5'-triphosphate analogues in which the β,γ-bridging oxygen has been replaced with a CXY group are useful chemical probes to investigate DNA polymerase catalytic and base-selection mechanisms. A limitation of such probes has been that conventional synthetic methods generate a mixture of diastereomers when the bridging carbon substitution is nonequivalent (X ≠ Y). We report here a general solution to this long-standing problem with four examples of β,γ-CXY dNTP diastereomers: (S)- and (R)-β,γ-CHCl-dGTP (12a-1/12a-2) and (S)- and (R)-β,γ-CHF-dGTP (12b-1/12b-2). Central to their preparation was conversion of the prochiral parent bisphosphonic acids to the P,C-dimorpholinamide derivatives 7 of their (R)-mandelic acid monoesters, which provided access to the individual diastereomers 7a-1, 7a-2, 7b-1, and 7b-2 by preparative HPLC. Selective acidic hydrolysis of the P-N bond then afforded "portal" diastereomers, which were readily coupled to morpholine-activated dGMP. Removal of the chiral auxiliary by H(2) (Pd/C) gave the four individual diastereomeric nucleotides 12, which were characterized by (31)P, (1)H, and (19)F NMR spectroscopy and by mass spectrometry. After treatment with Chelex-100 to remove traces of paramagnetic ions, at pH ~10 the diastereomer pairs 12a,b exhibit discrete P(α) and P(β)(31)P resonances. The more upfield P(α) and more downfield P(β) resonances (and also the more upfield (19)F NMR resonance in 12b) are assigned to the R configuration at the P(β)-CHX-P(γ) carbons on the basis of the absolute configurations of the individual diastereomers as determined from the X-ray crystallographic structures of their ternary complexes with DNA and polymerase β.

Supramolecular Photochirogenesis with Novel Cyclic Tetrasaccharide: Enantiodifferentiating Photoisomerization of (Z)‐Cyclooctene with Cyclic Nigerosylnigerose‐Based Sensitizers

Isophthalic and terephthalic acid monoesters of cyclic nigerosyl-(1→6)-nigerose (CNN), a cyclic tetrasaccharide composed of four d-glucopyranosyl residues connected by alternating α-1,3- and α-1,6-linkages, were synthesized as novel chiral supramolecular sensitizers for enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to planar chiral (E)-isomer (1E). Despite the saucer-shaped shallow cavity of CNN that does not immediately guarantee strong ground-state interactions with 1Z, the sensitizer-appended CNNs afforded optically active 1E in such enantiomeric excesses that are much improved than those obtained with an α-cyclodextrin analog and comparable with those obtained with a β-cyclodextrin analog. Interestingly, the enantiomeric excess values obtained were a critical function of temperature and solvent to show an inversion of the product chirality by changing the environmental variants. Nevertheless, all of the differential activation parameters calculated from the temperature-dependent enantiomeric excesses gave an excellent compensatory enthalpy-entropy relationship, indicating an operation of a single enantiodifferentiating mechanism in the present chiral photosensitization with modified CNNs.

3-Ethoxycarbonyl-2-hydroxy-6-methoxy-4-methylbenzoic acid

The title compound, C12H14O6, a substituted isophthalic acid monoester which was isolated from the lichen Thamnolia vermicularis var. subuliformis, displays intra­molecular carbox­yl–meth­oxy O—H⋯O and hy­droxy–carboxyl O—H⋯O hydrogen-bonding inter­actions. The terminal methyl group of the ethyl ester is disordered over two sets of sites with occupancies of 0.599 (19) and 0.401 (19).

ChemInform Abstract: Synthesis of Diverse Spiroisoxazolidinohydantoins by Totally Regio‐ and Diastereoselective 1,3‐Dipolar Cycloadditions.

AbstractTitle compounds are produced from 5‐carboxymethylene hydantoins generated by reaction of carbodiimides and acetylenedicarboxylic acid monoesters under mild conditions.